Oven control



May 16, 1939. c. THIEM 2,158,160

OVEN CONTROL Filed Aug. 26, 1957 Z'Sheets-Sheet l lll/ IN VENTOR. C'HKLUfff/1,

ATTORNEY.

Ill

IIIIIIIIII -May 16, 1939. r C, 'rl-"EM 2,158,160

' OVEN CONTROL A Filed Aug. 26, 1957 2 Sheets-Sheet 2 53 INVENTOR.

ATTORNEYS.

Patented May 16, 1939 UN1TED STATES PATENT ori-ICE ovm: commi.

y Carl Thiem, Greentown, Ind., assigner to Globe American Corporation,Kokomo, Ind., a corporation This invention relates to an oven controlsimilar in general principles'to that disclosed in copending applicationof Alden P. Chester, Serial No. 75,146, ledApril 18, 1936.

In said copending application-there is disclosed a combination ofthermostatic and timed control for an oven in which both the rate ofheat supply and the time of 'heat supply to an oven are automaticallycontrolled to produce uniform cooking results. Heat is supplied to theoven at a predetermined rate thermostatically controlled and the supplyof heat is shut ofi after a predetermined time interval. At the sametime, the circulation of air about the oven is shut off to permit theoven to continue cooking on retained heat. To this end there is provideda thermostatically controlled valve designed to control the admission offuel to maintain a predetermined oven temperature after the oven hasbeen heated, combined with a second valve arranged to shut off theheatsupply at the end of a predetermined time. Operating with the the secondmentioned valve there is a vent closure which shuts off the circulationof products of combustion at the same time the fuel supply s stopped.This eiectively retains a large amount of heat inthe oven and permitsthe same to continue cooking on the retained heat for a considerablelength oi time. The time of cooking on retained heat is, of course,dependent on the temperature within the oven at .the time of fuelshut-ofi and may be accurately determined by setting the thermostaticvalve to maintain the necessary temperature prior to shutoff. l'

One object ofthe present invention is to provide an improvedmechanism'ior operating the time control of fuel shutoff and ventclosure.

Another object is toprovide mechanical means as distinct from electricalmeans for operating said time control.

Other objects and features of the invention will be understood from theaccompanying drawings and the following description and claim:

Fig '1 is a vertical sectional View of a part of 45 an oven controlhaving the invention applied thereto. Fig; 2 is a plan view thereof*partly in section. Fig. 3 is an elevational View of the mechanism usedfor operating the time control. Fig. 4 is a sectional view takensubstantially on 50 the llines 4-4 of Figs. 1 and 2. Fig. 5 is asectional View taken `on the lines 5'-5 of Figs. l and 2. Fig. 6 is asimilar view taken 0n` the lines 6-6 of Figs. 1 and 2. Fig. 7 isan-elevational view of a clock used for the timingoperation. Fig. 8 is a55 sectional'view taken on the line 8--8 of Fig. 1.

Fig. 9 is a sectional view on the line 9-9 of Fig. 1. A In Fig. 1, thereis shown, by way of illustration, a .portion of a gas burning cook stovehaving an oven chamber I0 which is preferably of the type sealed fromcontact with the products of combustion, although the invention isequally applicable to the type of oven in which the products ofcombustion pass through the oven. Beneath the oven chamber there is aburner chamber Qnot shown) having a burner of any desired. form. Theproducts of combustion pass upwardly about the sides of the oven to achamber I3 above the same from which they may be discharged throughy aVent opening IB to a passage I5 when a vent closure I6 is elevated. Thepassage I5 may be connected to a chimney orother suitable disposalapparatus.

'I'he passage ,I5 is preferably formed-by a pair oi castings Il and I8,the casting Ilcontaining the vent opening I4 and the casting I8supporting the principal parts of the control apparatus. The casting I8has secured thereto 'a pair of upright brackets l@ which carryball'bearings 20 rotatably supporting a tubular shaft ZIK. The shaft 2|is connected by means of a semi-flexible coupling 22 to a similar shaft23 extending toward the front of the stove. The shaft 23 finds a bearingin the front plate 24 of the stove, as best seen in Fig. 2. Near thefront end of the stove there is provided a collar 25 xed to the shaft 23and having an arm 26 to which there is fastened a pin 2] whichterminates in a. knob 28 extending through a slotted opening in thefront plate 24. By means of the knob 28 the shafts 23 and 2| may berocked through a desired angle.

l, The shaft 2| has secured thereto a cam 30 adapted to engage a roller3l secured to the end of a stud 32. The-stud 32' is slidably mounted ina bushing 33 carried upon a bracket 34 in turn mounted upon thecasting'l. A valve body 35 is likewise' secured to the bracket 34, aflexible dia- Y! phragm 36 lbeing interposed between the valve body andthe bracket. A valve stem 31 is secured to the diaphragm 38 and ahuts atone end against the stud 32, being retained in engagement there- Awithby a spring 38. The valve stem 31 carries a valve member 39 engaginga'seat 40. An inlet pipe 4I for the valve 35 leads from any suitablefuel supply, Such as-.a gas main, and the outlet pipe 42 thereof leadsto a thermostatically controlled valve 43.

By means of theconstruction just described, the

valve 35 may be opened by moving the knob 28 clockwise from theolfposition .shownin Fig. 2 to an on position, the cam 30 in this move-.surface of the cam 44.

ment engaging the roller 3| to press the valve Y member 39 to the rightin Fig. 4.

The shaft 2| alsocarries a cam 44 shaped as best seen in Fig. .5. Avertical slide 45 having an opening 46 straddling the shaft 2| carries aroller 41 engaging the surface of the cam 44. The lower end of the slide45 is bent as shown in Fig. 1 andhas secured thereto a vertical stem 46upon which is mounted the vent closure I6. 'Ihe cam 44 isin the positionshown in Fig. 5 when the knob 26 is in the off position. When the knob28 is turned to the on position, the roller 41 rides on the edge of thecam 44 which is so shaped that the vvent closure I6 is lifted from thevent opening i4 to .permit circulation of the products of combustion.

The shaft 2| also carries a disc 49 having one or more projecting teeth5|!l engageable with a similar tooth or teeth 5| on the upper end of astem 52. The stem 52 is normally pressed upwardly by a spring 53bringing the teeth into engagement with the surface oi the disc 49. Theupward movement. of the stem 52 is limited by a washer 54 secured tothelower end thereof and engaging a plate 55 secured to the casting |1.When the knob 26 is in the ofi position shown in Fig. 2, the disc 49 isin the position shown in Fig. 6. When knob 26 is moved to the onposition, the disc 49 is rotated to bring the teeth '50 into engagementwith the teeth 5|, thus retaining the shaft 2| in the on position untilthe stem 52 is depressed by means to be hereinafter described.

A flat coil spring 56 has one end secured to the shaft 2| and the otherend secured by means of a screw 51 to the bracket I9. This spring is soarranged that it resists movement of the shaft 2| to the on position andserves to return said shaft to the oil position when the stem 52 isdepressed to release the teeth 56 and 5|. In this return movement, thevalve 35 and the vent opening i4 are-automatically closed. The returnmovement is limited by a stop 56 mounted on the casting I6 .and engaginga projection 59 formed on the rear l 'I'hus the teeth 56 and 5|constitute a latch retaining the vent closure and valve 35 in the openposition until stem 52 isdepressed'. Y

The thermostatic valve 43 receives its fuel vsui)- ply from the valve 35through pipe 42 and discharges to a pipe 60 which leads by anyconvenient'route to the oven burner. The valve is provided with aby-pass 6| which supplies sufficient fuel to keep a minimunriame eventhough the valve itself is closed. f The interior of the valve as showninI Fig. 2 is divided linto two chambers 62 and 63 having. a valveopening 64 therebetween 'which may be closed by a4 valve member 65 urgedinto closing position lby a spring 66. A stem 6.1

abutting against the valve member 65 leads through a suitable opening inthe valve body and engages a plate66. The plate 66 is rigidly secured toa second plate 69 by means of bolts 10 and the plate- 69 is threadedlyengaged by a stem 1| abutting at its inner end against'a thermostatbellows 12. The bellows 12 abuts at its opposite end against astatioary'plate 13 secured to the valve body 43 by boltsV 14. lAcompression spring 15 is interposed between the plates 13. and 66. Thethermostat bellows has connected thereto the usual tube 16 leading to athermostat bulb 11 (Fig. 1) which is placed in any convenient positionwithin the oven. v The bulb 11 is filled with'the usual volatile fluidwhich exerts increasing internal pressure within the beuows 12 withincreasing temperature at the bulb 11. By this means, an increase oftemperature in the oven expandsV the bellows 12, pressing the stern 1|and the plates 69 and 63 to the left pressure of the spring 15determines the temperature at which the valve will be entirely closedand, what is equally important, it determines the amount of valveopening prior to reaching this temperature. With a given pressure onspring 15, the thermostaticvalve is, therefore, operated to raise thetemperature of th'e oven to a predetermined degree at a predeterminedrate and to thereafter hold the oven at that temperature by repeatedopening and closing of the valve until the fuel supply' is shut oil bythe closure of valve 35. l

In order to change the temperature for which the thermostat is set andthe rate of temperature increase, it is onlynecessary to rotate the stem1|, thus increasing or decreasing the pressure on the bellows 12 and thespring 15. vTo accomplish this adjustment, there is provided a shaft 16coupled to the stem 1|n by means of a, coupling 19 having pin-and-slotconnection 66 with the stemV 1| which permits the stem to movelongitudinally. 'I'he shaft 16 nds a bearing 6| in the front plate 24 ofthe stove and finds another bearing in 'a spacer 62 which extendsbetween the shaft 23 and the shaft 16, both shafts being rotatabletherein. A sprocket 33 is fixed to the shaft 16 and carries a chain 64connected to a similar sprocket 65 rotatable on the shaft 23.

66 lto a knob 61, likewise rotatable on the shaft 23.' 'Thev pin 66passes through a suitable slotted opening the front plate 24. The knobl1 is provided with 'suitable graduations registering with an arrow orother index on the front plate to indicate the temperature at which itis desired to maintain the oven before the fuel supply vis turned off.'I'he spring 15 is so adjusted by means of lock nuts 96 that thethermostatic valve 43 will be operated to hold the desired temperatureas indicated by these graduations when once this temperature has beenreached.

For many purposes,l the type of thermostat control described in detailabove is not necessary. For example. a common form of snap actionthermostat which alternately fully opens and closes its valve may becombined-with a permanently burning pilot adjacent the oven burner toproduce satisfactory results.

' In order to trip the valve 35 and close the vent |6- when the desiredtemperature has been reached andmaintained for the proper length oftime, there is provided a lever 9| pivotally mounted at 92 upon abracket 93 secured to the casting I6. One end of said lever ispositioned to engage the upper end of --the stem .52 to press the samedownwardly. The opposite end of said lever is formed asa fork andengages one arm 94 of a bell crank lever 95.` The last mentioned lever`'is pivotally mounted at 96 Aupon the bracket`4 93 and has an arm 91extending upwardly.

For controlling the time of shutoff of the fuel and vent; there isprovided a clock 93 which is suitably mounted on a back plate 69 of thestove, preferably ,above the oven and in an accessible position. 'I'heclock 96 is of a common commer-V cial form-provided with a dial |00, anda pointer |0| and has the usual time train and alarm train,eachoperated' by an independent spring. The dial |00 is providedwith-graduations arranged in clockwise order from a zero position at thetop. The graduations preferably indicate one hours time. In theoperation of the clock, the pointer 0| is turned clockwise to agraduation corresponding to the time of heat supply desired. Thisclockwise movement of the pointer winds both the time' spring and thealarm spring. The

. time spring then runs the pointer counterclockwise until the zeroposition is reached, whereupon the alarm train is released and the alarmshaft is rotated. The type of clockv just described' is a commoncommercial article and for that reason thedetails thereof are not shownin the drawings.

|03 having a projection |04. 'I'he projection |04 is adapted to engage aprojection |05 carried by a sleeve |06 which is rotatably mounted on avertical stem |01. The vertical stem |01 .is rotatably mounted on abracket |08 secured to the back of the clock98 and longitudinal movementthereof is preventedby a pair of collars |09 and ||0 secured thereto.Rotational movement of the stem |01 is limited by stop pins carried bythe bracket |08 and engaging a pin ||2 carried by' the stem |01. roundsthe upper end of the stem |01 and has one end engaging the pin ||2 andthe other end engagingthe projection |05. Said spring normally urges thecollar `|06 in a clockwise direction on said stem.

The collar |06 carries a downward projection ||4, best seen in Fig. 8,which is adapted to engage anupward projection ||5 on the collar |09.

The upward projection ||5 is preferably semicircular in form, while thedownward projection ||4 occupies considerably-.less than a semicircleand thus provides lost motion between said collars. 'I'he spring ||3normally retains saidV projections in the position shown in Fig. 8, inwhich position the projection |05 is in the path of the projection |04.With the parts in this relation, counterclockwise rotation of the disc|03 causes the projection |04 to strike projection |05 and to rotate thecollar |06 and the stem |01 in the clockwise direction. In a clockwiserotation of the disc |03, however, the projection |04 engages projection|05 on theopposite face and merely turns the .collar |06 on the stemj|01against the action of spring ||3 without rotating the stem |01, saidstem being held against rotation by one of the stop pins When the alarmtrain has not been wound, the projection |04 occupies a position such asshown in Fig. 9,. In the winding of the alarm spring, the disc |03 isrotated clockwise until projection |04 has passed projection |05.Thereafter, when the alarm is tripped, the unwinding of its springrotates the disc |03 in the counterclockwise direction to .cause theprojection |04 to strike projection |05 and to rotate the stem |01. Inorder that pro-v jectioii '|04.may pass projection |05 in the winding'ofthe alarm train, the pointer |0| must be moved at least a predetermineddistance, pref J erablypast'the graduation indicating 20 minutes.

.If a smaller time isto be used, the pointer may. then I 'returned'to'the proper graduation with-A outmovingithe disk |03. v

vThe stem L01.L has a pin-and-slot connection A torsion spring ||3 sur-||8 pivotally mounted on a bracket' I9. Downward movement of the stemIII is prevented by 'a collar |20. The sleeve ||1 provides an extensibleconnection whichpermits the clock tol be mounted at any desired heightto t various de- 5 signs of stoves and also acts as a partial universaljoint. By means of this connection, rotation of the stem |01 causessimilar rotation of the stem IIB. The lower end of the stem ||8 isoutwardly bent as shown at |2| and is connected by a link l0 |22 withthe upper end of the lever arm 91.

By means of the construction just described, the clock 98 may be setwith its pointer |0| on a graduation corresponding to any desired periodof time. At the lconclusion of that period, the l5 alarm train istripped, disc |03 is rotated, projection |04 strikes projection |05 torotate the collar |06 and stem |01. Rotation of stem |01 rotates stem||8 and pulls the link |22 to the right in-Flg. 1. The movement of link|22 rocks the bell crank 20 which in turn presses the lever 9| down onthe upper end of the stem 55, thus disengaging the latch teeth 50 and 5|and permitting spring 56 to shut off the fuel and to close the vent I6.In Fig. 1 the position of parts is shown at the 25 instant of thisoperation. In the operation of the oven, the clock pointer is first setto the desired time for fuel supply and the knob 28 is then set inposition to open the valve 35 and vent. I6. The knob 61 is turned 3 0 tothe proper position for the desired oven teml perature. The oven burneris then lighted and the oven temperature will be raised at a prede-'termined rate to the desired temperature and will be maintained atthetemperature until the 35 clock has returned the pointer to the zeroposition. When this occurs, the alarm train of the clock is tripped andthe valve 35 and vent I6 are closed, as previously described.Thereafter, the oven continues to cook on retained heat for an 40appreciable predetermined period since all c irculation of air or othergas around lthe oven is stopped by the vent closure.

In order to close the valve 35 and vent I6 manually, there is provided astem |24 extending completely through the tubular shafts 2| and 23 andterminating in a button |25 inset in a recess in the knob 81. The stem|24 is normally pressed to the left in Figs. 1 and 2 by a compressionspring 4|26 abutting against a washer |21 secured to said 50 stem andagainst a washer |28 secured in the end of the tubular shaft 2|. Whenthe button |25 is manually pressed, the stem |24 engages the lever arm91 and. moves the lever 9| to trip the valve and vent closure. in thesame manner as 56 donev by the clock 923.r i

W'hile the foregoing specification describes in detail a preferred formof the invention, the construction thereof may be varied by thoseskilled in the art Without departing from the scope of 00 the inventionas dened by the appended claim. For example, cthe invention is not to belimited to gas stoves. It is equally applicable to stoves using othertypes of fuel and certain features thereof are applicable toelectrically heated ovens. 05 In the claim, the word fuel is .intendedto include electric current and the linesand "valves" include theequivalent conductors and switches for use ,with an electricv heater.'I'he inventionv is also applicable to ovens heated by coal, wood 70 erwhich may be opened or closed by the mechanism herein described to cutoi the heat supply.`

. rection in the winding of said clock mechanism,

astriker carried by said alarm shaft and rotatable thereby, a stemmdunted for limited rotative movement about its axis, a member mountedon said stem and having vlimited rotative movement thereon, resilientmeans normally retaining said member at one limit of its rotativemovement, whereby further movement thereof moves said stem, andconnections between said stem and said latchby means of which said latchis tripped to permit said controlling means to shut o' said heat supplywhen said shaft is rotated in the irst direction, said member having aprojectionI normally in the path of said striker and beingmoved therebyto trip said latch when said alarm shaft is moved in the rst mentioneddirection and being moved upon said stem against the actionlof saidresilient means when engaged by said striker in its movement in thesecond direction.

CARL THIEM.

